A failed asylum-seeker was handed thousands of pounds in compensation yesterday by European judges who claimed British law had failed to protect her from being treated as a slave.

The Ugandan came to Britain illegally on a false passport, became a care worker and was free to leave the house where she worked, the European Court of Human Rights heard.

Police investigating the 33-year-old's case decided she was a criminal and a British judge cast doubt on her credibility, describing her story as 'implausible'.

Controversial: An illegal immigrant was today handed thousands of pounds in compensation by European human rights judges on the grounds that British law failed to protect her from slavery. The European Court of Human Rights is pictured

But the Strasbourg judges ruled that the woman, whose identity they shielded, suffered a breach of her rights as there was no UK law at the time specifically banning slavery. They ordered the Government to pay her £23,500, made up of £7,000 in compensation and £16,500 in expenses and costs.

The judgment marks another case in which Britain has been told that Acts of Parliament and common law have been inadequate to meet European demands.

Since then, the 2009 Coroners and Justice Act has been passed which specifically outlaws slavery.

However, Prime Minister David Cameron remains at odds with Strasbourg over the human rights judges' demand that Britain allows convicted prisoners to vote.

The woman in the slavery case – identified only as CN – came to this country in 2002 on a false passport and visa provided by her uncle, identified only as PS.

He set her up as a care worker for an Iraqi couple in Leeds and £1,600 a month was paid for the work.

But, the woman alleged, the money was given to her uncle and she was never paid more than £20 or £40 when she was given an afternoon off each month.

Frustration: David Cameron remains at odds with Strasbourg over the human rights judges' demand that Britain pass laws to allow convicted prisoners to vote in elections

She did not complain until 2006, four years later, when she collapsed in a bank and was treated in hospital after it was discovered she was HIV positive.

CN was given a flat by her local council, but her application for asylum, on the grounds she had fled sexual and physical violence in Uganda, failed.

Police investigations ended in 2009 following two inquiries into the woman's complaints that she was held as a slave. A report from the Metropolitan Police Human Trafficking Team noted that she had been refused legitimate entry into Britain and had come in with a false passport and forged visa.

The woman had been paid through her relative 'in order to hide from the authorities the fact that the victim did not have a national insurance number'.

The report went on: 'If money was paid to her, then she would have had to pay tax and her false identity would have come to the notice of the tax office. This would then lead to her arrest and eviction from the UK.

'There is no evidence to show that this female is a victim of slavery or forced labour. She willingly worked and was paid but she chose that the money should go to her uncle to conceal being in the UK. It is basically a situation that one criminal, her uncle, has taken all the proceeds of their crime.'

The British judge who heard CN's asylum appeal 'expressed serious concerns about the applicant's credibility and found much of her account to be implausible', the Strasbourg court heard.

But the European judges said that, because police investigated the complaints, they could not have been considered implausible. They insisted that the woman's complaints were credible.

The court added that the inquiry should not have been carried out by a police unit dealing with human trafficking rather than slavery.

Britain was also obliged to prosecute any act aimed at enforcing slavery. The country's law was 'inadequate' for the purpose, the European judges declared.